The project under development attempts to contribute to the understanding of the process by which corneal hydration is maintained by its limiting layers, in particular the endothelium. The endothelium fluid pump is studied from several perspectives. The rate of fluid transport across endothelium is measured, as well as osmotic flows imposed and the transport-related electrical potential difference across the layer, and also its electrical resistance and intracellular potentials. The influence of nutrients, drugs and ionic composition of the media on this system are analyzed. All the information will be integrated into the context of a working model of endothelial function.